The U.N. envoy to Syria is making an unannounced visit to Damascus for talks on implementing a cease-fire set to start later this week.

The envoy, Staffan de Mistura, arrived late Monday in the Syrian capital, where he is expected to meet with Syrian government officials.

World powers agreed last week to a cessation of hostilities, set to begin Friday, in order to let badly needed humanitarian aid be delivered.

The cease-fire is meant to help make it possible to resume international peace talks that collapsed after just three days earlier this month in Geneva.

Since then, the violence has shown no signs of letting up. The Syrian government has continued an offensive backed by Russian airstrikes. A wide array of rebel groups also continue to fight within the country, each with different objectives and international backers.

World powers have said they hope to resume peace talks by the end of the month.